Originally built as the entrance to the Welland "feeder" canal, the town once boasted several water-powered mills and a once-bustling canal port. The feeder canal closed in the late 1880s and the last mill was destroyed and replaced with a condominium complex about 10 years ago.
There is an impassable dam at Dunnville which regulates the level of the Grand River at Port Maitland which, in the 19th century, also helped regulate the level of the Welland Canal (from 1829 until 1887 when the (3rd) canal began to intake its water directly from lake Erie).

Only a few kilometres from Lake Erie, Dunnville has many private vacation properties.

Bick's Pickle Factory, Dunnville's largest factory, provides employment for a small percentage of the town's population, mainly students.